3 /* a generic and efficient heap */
5 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved. */
7 /* This program is free software; you can redistribute it and/or modify it
8 * under the terms of the license (GNU LGPL) which comes with this package. */
10 #include "xbt/sysdep.h"
12 #include "heap_private.h"
15 /** @addtogroup XBT_heap
16 * \brief This section describes the API to generic heap with O(log(n)) access.
20 * @brief Creates a new heap.
21 * \param init_size initial size of the heap
22 * \param free_func function to call on each element when you want to free
23 * the whole heap (or NULL if nothing to do).
27 xbt_heap_t xbt_heap_new(int init_size, void_f_pvoid_t * const free_func)
29 xbt_heap_t H = xbt_new0(struct xbt_heap, 1);
32 H->items = (xbt_heapItem_t) xbt_new0(struct xbt_heapItem, init_size);
38 * @brief kilkil a heap and its content
39 * @param H poor victim
41 void xbt_heap_free(xbt_heap_t H)
45 for (i = 0; i < H->count; i++)
46 H->free(H->items[i].content);
53 * @brief returns the number of elements in the heap
54 * @param H the heap we're working on
55 * @return the number of elements in the heap
57 int xbt_heap_size(xbt_heap_t H)
63 * @brief Add an element into the heap.
64 * \param H the heap we're working on
65 * \param content the object you want to add to the heap
66 * \param key the key associated to this object
68 * The element with the smallest key is automatically moved at the top of the heap.
70 void xbt_heap_push(xbt_heap_t H, void *content, double key)
72 int count = ++(H->count);
76 H->size = 2 * size + 1;
78 (void *) realloc(H->items,
79 (H->size) * sizeof(struct xbt_heapItem));
81 item = &(H->items[count - 1]);
83 item->content = content;
84 xbt_heap_increaseKey(H, count - 1);
89 * @brief Extracts from the heap and returns the element with the smallest key.
90 * \param H the heap we're working on
91 * \return the element with the smallest key
93 * Extracts from the heap and returns the element with the smallest
94 * key. The element with the next smallest key is automatically moved
95 * at the top of the heap.
97 void *xbt_heap_pop(xbt_heap_t H)
106 H->items[0] = H->items[(H->count) - 1];
108 xbt_heap_maxHeapify(H);
109 if (H->count < H->size / 4 && H->size > 16) {
110 H->size = H->size / 2 + 1;
112 (void *) realloc(H->items,
113 (H->size) * sizeof(struct xbt_heapItem));
119 * @brief returns the smallest key in the heap (heap unchanged)
120 * \param H the heap we're working on
122 * \return the smallest key in the heap without modifying the heap.
124 double xbt_heap_maxkey(xbt_heap_t H)
126 xbt_assert0(H->count != 0,"Empty heap");
131 * @brief returns the value associated to the smallest key in the heap (heap unchanged)
132 * \param H the heap we're working on
134 * \return the value associated to the smallest key in the heap
135 * without modifying the heap.
137 void *xbt_heap_maxcontent(xbt_heap_t H)
139 xbt_assert0(H->count != 0,"Empty heap");
140 return CONTENT(H, 0);
144 * \param H the heap we're working on
146 * Restores the heap property once an element has been deleted.
148 static void xbt_heap_maxHeapify(xbt_heap_t H)
155 int count = H->count;
156 if (l < count && KEY(H, l) < KEY(H, i))
158 if (r < count && KEY(H, r) < KEY(H, greatest))
161 struct xbt_heapItem tmp = H->items[i];
162 H->items[i] = H->items[greatest];
163 H->items[greatest] = tmp;
171 * \param H the heap we're working on
172 * \param i an item position in the heap
174 * Moves up an item at position i to its correct position. Works only
175 * when called from xbt_heap_push. Do not use otherwise.
177 static void xbt_heap_increaseKey(xbt_heap_t H, int i)
179 while (i > 0 && KEY(H, PARENT(i)) > KEY(H, i)) {
180 struct xbt_heapItem tmp = H->items[i];
181 H->items[i] = H->items[PARENT(i)];
182 H->items[PARENT(i)] = tmp;